A series of experiments is proposed to study drug dissociation, drug discrimination and their central nervous system (CNS) correlates in goldfish, rats and monkeys. The proposed research is comprised of four major and interrelated series of investigations: (1) relation of age and environmental variables to dissociation, (2) relation of task variables to dissociation, (3) relation between dissociation and discriminations based on drug states, and (4) central nervous system correlates of dissociation. (1) We will examine the influence of age of learning and length of retention interval on retention for responses learned either in a drug or normal state. We will also vary environmental complexity during the retention interval in order to assess interference effects upon forgetting. (2) To relate task variables and dissociation, we will study (a) dissociation of Pavlovian autonomic versus operant responses, (b) external stimulus variables in state dependency, (c) dissociation for higher order learning, and (d) a proposed dual-process attentional model for dissociation. (3) Our investiation of the relation between discriminations based on drug states and dissociation will address three basic issues: (a) the establishment of detection and behaviorally toxic discrimination thresholds for several standard dissociative drugs, (b) the possibility of training different responses to different drug states, or levels of a single drug, and (c) the possibility that drug dissociation is based upon the discriminable properties of drugs. (4) Study of central nervous system correlates of dissociation will focus on (a) neuroanatomical studies utilizing lesions of the central nervous system, and (b) electrophysiological studies of activity recorded during training and overtraining of dissociated learning.